The clinical significance of neutrophilic pleocytosis in cerebrospinal fluid in patients with viral central nervous system infections

Lessons Learned from West Nile Virus Infection:Vaccinations in Equines and Their Implications for One Health Approaches

Humans and equines are two dead-end hosts of the mosquito-borne West Nile virus (WNV) with similar susceptibility and pathogenesis. Since the introduction of WNV vaccines into equine populations of the United States of America (USA) in late 2002, there have been only sporadic cases of WNV infection in equines. These cases are generally attributed to unvaccinated and under-vaccinated equines. In contrast, due to the lack of a human WNV vaccine, WNV cases in humans have remained steadily high. An average of 115 deaths have been reported per year in the USA since the first reported case in 1999. Therefore, the characterization of protective immune responses to WNV and the identification of immune correlates of protection in vaccinated equines will provide new fundamental information about the successful development and evaluation of WNV vaccines in humans. This review discusses the comparative epidemiology, transmission, susceptibility to infection and disease, clinical manifestation and pathogenesis, and immune responses of WNV in humans and equines. Furthermore, prophylactic and therapeutic strategies that are currently available and under development are described. In addition, the successful vaccination of equines against WNV and the potential lessons for human vaccine development are discussed.

A Specific Pattern of Routine Cerebrospinal Fluid Parameters Might Help to Identify Cases of West Nile Virus Neuroinvasive Disease

BACKGROUND

Viral meningitis/encephalitis (ME) is a rare but potentially harmful disease. The prompt identification of the respective virus is important to guide not only treatment but also potential public health countermeasures. However, in about 40% of cases, no virus is identified despite an extensive diagnostic workup. The aim of the present study was to analyze demographic, seasonal, and routine cerebrospinal fluid (CSF) parameters in cases of viral ME and assess their utility for the prediction of the causative virus.

METHODS

Demographic data, season, and routine CSF parameters (total leucocytes, CSF cell differentiation, age-adjusted CSF/serum albumin ratio, and total immunoglobulin ratios) were retrospectively assessed in cases of viral ME.

RESULTS

In total, 156 cases of acute viral ME (74 female, median age 40.0 years) were treated at a tertiary-care hospital in Germany. Specific viral infections were detected in 93 (59.6%) cases. Of these, 14 (9.0%) cases were caused by herpes simplex virus (HSV), 36 (23.1%) by varicella-zoster virus (VZV), 27 (17.3%) by enteroviruses, 9 (5.8%) by West Nile virus (WNV), and 7 (4.5%) by other specific viruses. Additionally, 64 (41.0%) cases of ME of unknown viral etiology were diagnosed. Cases of WNV ME were older, predominantly male, showed a severe disruption of the blood-CSF-barrier, a high proportion of neutrophils in CSF, and an intrathecal total immunoglobulin M synthesis in the first CSF sample. In a multinominal logistic regression analysis, the accuracy of these CSF parameters together with age and seasonality was best for the prediction of WNV (87.5%), followed by unknown viral etiology (66.7%), VZV (61.8%), and enteroviruses (51.9%).

CONCLUSIONS

Cases with WNV ME showed a specific pattern of routine CSF parameters and demographic data that allowed for their identification with good accuracy. These findings might help to guide the diagnostic workup in cases with viral ME, in particular allowing the timely identification of cases with ME due to WNV.

German guidelines on community-acquired acute bacterial meningitis in adults

INTRODUCTION

The incidence of community-acquired acute bacterial meningitis has decreased during the last decades. However, outcome remains poor with a significant proportion of patients not surviving and up to 50% of survivors suffering from long-term sequelae. These guidelines were developed by the Deutsche Gesellschaft für Neurologie (DGN) under guidance of the Arbeitsgemeinschaft der Wissenschaftlichen Medizinischen Fachgesellschaften (AWMF) to guide physicians through diagnostics and treatment of adult patients with acute bacterial meningitis.

RECOMMENDATIONS

The most important recommendations are: (i) In patients with suspected acute bacterial meningitis, we recommend that lumbar cerebrospinal fluid (with simultaneous collection of serum to determine the cerebrospinal fluid-serum glucose index and blood cultures) is obtained immediately after the clinical examination (in the absence of severely impaired consciousness, focal neurological deficits, and/or new epileptic seizures). (ii) Next, we recommend application of dexamethasone and empiric antibiotics intravenously. (iii) The recommended initial empiric antibiotic regimen consists of ampicillin and a group 3a cephalosporin (e.g., ceftriaxone). (iv) In patients with severely impaired consciousness, new onset focal neurological deficits (e.g. hemiparesis) and/or patients with newly occurring epileptic seizures, we recommend that dexamethasone and antibiotics are started immediately after the collection of blood; we further recommend that -if the imaging findings do not indicate otherwise -a lumbar CSF sample is taken directly after imaging. (v) Due to the frequent occurrence of intracranial and systemic complications, we suggest that patients with acute bacterial meningitis are treated at an intensive care unit in the initial phase of the disease. In the case of impaired consciousness, we suggest that this is done at an intensive care unit with experience in the treatment of patients with severe CNS diseases.

CONCLUSIONS

The German S2k-guidelines give up to date recommendations for workup, diagnostics and treatment in adult patients with acute bacterial meningitis.

Distinguishing clinical characteristics of central nervous system tuberculosis in immunodeficient and non-immunodeficient individuals: a 12-year retrospective study

BACKGROUND

Central nervous system tuberculosis (CNS TB) is a severe Mycobacterium tuberculosis (MTB) infection. It is unclear whether a patient's immune status alters the clinical manifestations and treatment outcomes of CNS TB.

METHODS

Between January 2007-December 2018, chart reviews of CNS TB, including tuberculous meningitis (TBM), tuberculoma/abscess, and TB myelitis, were made. Subjects were categorized as immunodeficient (ID) and non-immunodeficient (NID).

RESULTS

Of 310 subjects, 160 (51.6%) were in the ID group-132 (42.6%) had HIV and 28 (9.0%) had another ID, and 150 (48.4%) were in the NID group. The mean age was 43.64 ± 16.76 years, and 188 (60.6%) were male. There were 285 (91.9%) TBM, 16 (5.2%) tuberculoma/abscess, and 9 (2.9%) myelitis cases. The TBM characteristics in the ID group were younger age (p = 0.003), deep subcortical location of tuberculoma (p = 0.030), lower hemoglobin level (p < 0.001), and lower peripheral white blood cell count (p < 0.001). Only HIV individuals with TBM had an infection by multidrug-resistant MTB (p = 0.013). TBM mortality was varied by immune status -HIV 22.8%, other ID 29.6%, and NID 14.8% (p < 0.001). Factors significantly associated with unfavorable outcomes in TBM also differed between the HIV and NID groups.

CONCLUSIONS

TBM is the most significant proportion of CNS TB. Some of the clinical characteristics of TBM, such as age, radiographic findings, hematological derangement, and mortality, including factors associated with unfavorable outcomes, differed between ID and non-ID patients.

Association of Scrub Typhus in Children with Acute Encephalitis Syndrome and Meningoencephalitis, Southern India

Scrub typhus is an established cause of acute encephalitis syndrome (AES) in northern states of India. We systematically investigated 376 children with AES in southern India, using a stepwise diagnostic strategy for the causative agent of scrub typhus, Orientia tsutsugamushi, including IgM and PCR testing of blood and cerebrospinal fluid (CSF) to grade its association with AES. We diagnosed scrub typhus in 87 (23%) children; of those, association with AES was confirmed in 16 (18%) cases, probable in 55 (63%), and possible in 16 (18%). IgM detection in CSF had a sensitivity of 93% and specificity of 82% compared with PCR. Our findings suggest scrub typhus as an emerging common treatable cause of AES in children in southern India and highlight the importance of routine testing for scrub typhus in diagnostic algorithms. Our results also suggest the potential promise of IgM screening of CSF for diagnosis of AES resulting from scrub typhus.

Cerebrospinal fluid analysis in emergency patients with suspected infection of the central nervous system

BACKGROUND AND PURPOSE

Meningitis and encephalitis are potentially life-threatening diseases that require fast and accurate diagnostics and therapy. The value of polymerase chain reaction (PCR) multiplex testing in clinical practice is still a matter of debate. This study aims to evaluate its benefits and limitations in emergency patients.

METHODS

We assessed the value of a meningoencephalitis PCR array in the clinical routine of an emergency department.

RESULTS

Of 1578 emergency patients who received a lumbar puncture, 43% received it for a clinically suspected central nervous system (CNS) infection. After initial workup for cerebrospinal fluid (CSF) cell count, protein and glucose, a CNS infection was still considered likely in 307 patients. In these patients, further microbiologic workup was performed. A total of 230 samples were examined by PCR and a pathogen was detected in 66 of these samples. In the case of a positive microbiologic result, a comparison between PCR array and standard method was available for 59 samples, which demonstrated an overcall agreement of 80% (n = 47/59). Of interest, exclusively array-positive results were observed for patients with meningitis found to be positive for Streptococcus pneumoniae; four out of five patients had been treated with antibiotics before the lumbar puncture. In samples with normal CSF cell count only two positive array results were obtained, both for human herpesvirus 6, and these were not clinically relevant.

CONCLUSION

Our data suggest that the array substantially contributes to a detection of pathogens in patients with suspected CNS infection and seems of particular interest in patients with acute bacterial meningitis under empiric antibiotic treatment. In CSF samples with normal cell count, it might be dispensable.

Etiology, Clinical Phenotypes, Epidemiological Correlates, Laboratory Biomarkers and Diagnostic Challenges of Pediatric Viral Meningitis: Descriptive Review

Meningitis is an inflammation of the brain and spinal cord meninges caused by infectious and non-infectious agents. Infectious agents causing meningitis include viruses, bacteria, and fungi. Viral meningitis (VM), also termed aseptic meningitis, is caused by some viruses, such as enteroviruses (EVs), herpesviruses, influenza viruses, and arboviruses. However, EVs represent the primary cause of VM. The clinical symptoms of this neurological disorder may rapidly be observed after the onset of the disease, or take prolonged time to develop. The primary clinical manifestations of VM include common flu-like symptoms of headache, photophobia, fever, nuchal rigidity, myalgia, and fatigue. The severity of these symptoms depends on the patient's age; they are more severe among infants and children. The course of infection of VM varies between asymptomatic, mild, critically ill, and fatal disease. Morbidities and mortalities of VM are dependent on the early recognition and treatment of the disease. There were no significant distinctions in the clinical phenotypes and symptoms between VM and meningitis due to other causative agents. To date, the pathophysiological mechanisms of VM are unclear. In this scientific communication, a descriptive review was performed to give an overview of pediatric viral meningitis (PVM). PVM may occasionally result in severe neurological consequences such as mental retardation and death. Clinical examinations, including Kernig's, Brudzinski's, and nuchal rigidity signs, were attempted to determine the clinical course of PVM with various success rates revealed. Some epidemiological correlates of PVM were adequately reviewed and presented in this report. They were seen depending mainly on the causative virus. The abnormal cytological and biochemical features of PVM were also discussed and showed potentials to distinguish PVM from pediatric bacterial meningitis (PBM). The pathological, developmental, behavioral, and neuropsychological complications of PVM were also presented. All the previously utilized techniques for the etiological diagnosis of PVM which include virology, serology, biochemistry, and radiology, were presented and discussed to determine their efficiencies and limitations. Finally, molecular testing, mainly PCR, was introduced and showed 100% sensitivity rates.

Aseptic Meningitis and Its Viral Etiologies, Clinical Characteristics and Management Practices in Children: A Retrospective Hospital-Based Study From Jordan

Purpose In this study, we aimed to describe the clinical characteristics, laboratory findings, aetiologies, and role of PCR in the decision on the management plan and duration of hospital stay in Jordanian children diagnosed with aseptic meningitis. Methods This retrospective observational cohort study included children diagnosed with meningitis who were admitted to the paediatric ward at Jordan University Hospital (JUH) during the period from January 2016 to August 2020. Patients were identified through the ICD9 discharge code of meningitis. Patients diagnosed with aseptic meningitis (defined as a patient with signs and symptoms of meningitis with a cerebrospinal fluid (CSF) white cell count of >5 cells/mm3, and a negative CSF Gram stain) were included, while patients who had low CSF glucose (<50% of serum) positive cerebrospinal fluid Gram stain and/or culture for bacterial meningitis were excluded. Files were reviewed to collect data on the clinical picture, viruses identified by the CSF viral polymerase chain reaction (PCR) panel, duration of medication, and hospital stay in patients with identified virus versus those with negative viral PCR. Results One hundred and thirty-one patients were included: 87 males (66.4%) and 44 females (33.5%). Fever was the most common presenting symptom, followed by headache, vomiting, and excessive sleep in 48.0%, 42.7%, and 35.8% of the patients, respectively. Prior oral antibiotic use was reported in 48/125 (38.4%) patients. White blood cell count (WBC) ranged from 4.800 to 22.000. cells/mL, 45 patients (34.3%) had counts above 15.000 cells/mL. C-reactive protein level was high in 61/103 (59.2%) patients. CSF WBC count was <100 in 62 (47.3%) patients while neutrophils predominance of >70% was present in 27 (20.6%) patients. Viral panel PCR was done for 100/131 (76.3%) patients and was positive in 66/100 (66%) patients; with enterovirus being the most common identified viruses (60/100; 60%). The average duration of hospital stay was 5.9 and 5.5 days for those with negative and positive PCR respectively. Ten (7.6%) patients had seizures upon presentation. None of the patients had any neurological sequel related to his meningitis. Conclusion Enteroviruses are the most common identified cause of paediatric aseptic meningitis in Jordan. Although PCR revealed an identified virus in around half of the patients, nevertheless, there was no adjustment in the management plan regarding duration of empirical antibiotic use and hospital stay. Increasing knowledge and awareness among clinicians on viral meningitis' lab characteristics might have great impact on duration of hospital stay and thus would be reflected on the patient and the healthcare system as well.

A Case Report of Antibiotic-Induced Aseptic Meningitis in Psoriasis

Although frequently prescribed, certain antibiotics such as trimethoprim-sulfamethoxazole carry the risk of a rare yet life-threatening adverse effect, termed drug-induced aseptic meningitis. Morbidity can be avoided if the medication is identified and discontinued. Patients in reported cases tend to be female and have an autoimmune disease or prior adverse reaction to the offending agent. As a rare and poorly characterized condition, the subset of patients using antibiotics at risk for aseptic meningitis remains unclear; hence, cataloging these adverse events remains critical for better elucidating the disease. Here, we report a 62-year-old man with psoriasis and no prior history of sulfa allergy, who presented with a sudden onset of fever, chills, vomiting, and muscle aches 5 hours after taking single doses of trimethoprim-sulfamethoxazole and ciprofloxacin. Common infectious causes were ruled out, and his medications were discontinued. Despite initial symptom resolution with discontinuation, the patient neurologically deteriorated over the next two days before eventually recovering with supportive care. This case highlights the variable presentation of drug-induced aseptic meningitis. In contrast to previous reports of drug-induced aseptic meningitis, our patient was male, older than the median age of 40 years, and did not have a prior adverse reaction to the antibiotic. Furthermore, to the best of our knowledge, we report a possible case of antibiotic-induced aseptic meningitis in a patient with psoriasis. Lastly, the case emphasizes not only the value of a thorough medication history but also the importance of recognizing that patients may deteriorate in the first 48 hours before resolution.

Cerebrospinal fluid in COVID-19: A systematic review of the literature

OBJECTIVE

We sought to review the literature on cerebrospinal fluid (CSF) testing in patients with COVID-19 for evidence of viral neuroinvasion by SARS-CoV-2.

METHODS

We performed a systematic review of Medline and Embase between December 1, 2019 and November 18, 2020 to identify case reports or series of patients who had COVID-19 diagnosed based on positive SARS-CoV-2 polymerase chain reaction (PCR) or serologic testing and had CSF testing due to a neurologic symptom.

RESULTS

We identified 242 relevant documents which included 430 patients with COVID-19 who had acute neurological symptoms prompting CSF testing. Of those, 321 (75%) patients had symptoms that localized to the central nervous system (CNS). Of 304 patients whose CSF was tested for SARS-CoV-2 PCR, there were 17 (6%) whose test was positive, all of whom had symptoms that localized to the central nervous system (CNS). The majority (13/17, 76%) of these patients were admitted to the hospital because of neurological symptoms. Of 58 patients whose CSF was tested for SARS-CoV-2 antibody, 7 (12%) had positive antibodies with evidence of intrathecal synthesis, all of whom had symptoms that localized to the CNS. Of 132 patients who had oligoclonal bands evaluated, 3 (2%) had evidence of intrathecal antibody synthesis. Of 77 patients tested for autoimmune antibodies in the CSF, 4 (5%) had positive findings.

CONCLUSION

Detection of SARS-CoV-2 in CSF via PCR or evaluation for intrathecal antibody synthesis appears to be rare. Most neurological complications associated with SARS- CoV-2 are unlikely to be related to direct viral neuroinvasion.

Viral meningitis: an overview

Meningitis is a serious condition that affects the central nervous system. It is an inflammation of the meninges, which is the membrane that surrounds both the brain and the spinal cord. Meningitis can be caused by bacterial, viral, or fungal infections. Many viruses, such as enteroviruses, herpesviruses, and influenza viruses, can cause this neurological disorder. However, enteroviruses have been found to be the underlying cause of most viral meningitis cases worldwide. With few exceptions, the clinical manifestations and symptoms associated with viral meningitis are similar for the different causative agents, which makes it difficult to diagnose the disease at early stages. The pathogenesis of viral meningitis is not clearly defined, and more studies are needed to improve the health care of patients in terms of early diagnosis and management. This review article discusses the most common causative agents, epidemiology, clinical features, diagnosis, and pathogenesis of viral meningitis.

Eastern equine encephalitis and use of IV immunoglobulin therapy and high-dose steroids

OBJECTIVE

To determine the clinical presentation and patient outcomes after treatment with IV immunoglobulin (IVIG), high-dose steroids, or standard of care alone in Eastern equine encephalitis (EEE), a mosquito-borne viral infection with significant neurologic morbidity and mortality.

METHODS

A retrospective observational study of patients admitted to 2 tertiary academic medical centers in Boston, Massachusetts, with EEE from 2005 to 2019.

RESULTS

Of 17 patients (median [IQR] age, 63 [36-70] years; 10 (59%) male, and 16 (94%) White race), 17 patients had fever (100%), 15 had encephalopathy (88%), and 12 had headache (71%). Eleven of 14 patients with CSF cell count differential had a neutrophil predominance (mean = 60.6% of white blood cells) with an elevated protein level (median [IQR], 100 mg/dL [75-145]). Affected neuroanatomic regions included the basal ganglia (n = 9/17), thalamus (n = 7/17), and mesial temporal lobe (n = 7/17). A total of 11 patients (65%) received IVIG; 8 (47%) received steroids. Of the patients who received IVIG, increased time from hospital admission to IVIG administration correlated with worse long-term disability as assessed by the modified Rankin Scale (mRS) (r = 0.72, p = 0.02); steroid use was not associated with the mRS score. The mortality was 12%.

CONCLUSIONS

Clinicians should suspect EEE in immunocompetent patients with early subcortical neuroimaging abnormalities and CSF neutrophilic predominance. This study suggests a lower mortality than previously reported, but a high morbidity rate in EEE. IVIG as an adjunctive to standard of care may be considered early during hospitalization.

Pediatric Enteroviral Central Nervous System Infections in Bialystok, Poland: Epidemiology, Viral Types, and Drivers of Seasonal Variation

Enteroviruses are common causes of infections of the central nervous system (CNS) that in temperate climates tend to peak in the summer. The aim of the study was to describe epidemiology, drivers of seasonality, and types of enteroviruses causing infections of the CNS in children in Northeastern Poland. We prospectively collected data on children hospitalized with infection of the CNS attributed to enteroviruses in Bialystok, Poland, from January 2015 to December 2019. In total, 224 children were included. Nineteen different enterovirus types were identified in isolates collected from 188 children. Coxsackie B5 (32%), echovirus 30 (20%), and echovirus 6 (14%) were the three most common types. Enteroviruses were more prevalent during the summer–fall season. Infections caused by echovirus 30 peaked early in June and coxsackievirus B5 in July, whereas echovirus 6 peaked late in October. Phylogenetic analyses of these three enterovirus types showed multiple lineages co-circulating in this region. Mean air temperatures and precipitation rates were independently associated with monthly number of cases. Considering lack of effective treatment or vaccine, easy transmission of enteroviruses between susceptible individuals, their high mutation rate and prolonged time of viral shedding, continued monitoring and surveillance are imperative to recognize enteroviral infections of the CNS and the changes in circulation of enteroviruses in Poland.

Proteomic Analysis of Cerebrospinal Fluid in Children with Acute Enterovirus-Associated Meningoencephalitis Identifies Dysregulated Host Processes and Potential Biomarkers

Enteroviruses (EVs) are major causes of viral meningoencephalitis in children. To better understand the pathogenesis and identify potential biomarkers, cerebrospinal fluid proteome in children (n = 52) suffering from EV meningoencephalitis was compared to that in EV-negative control subjects (n = 53) using the BoxCar acquisition technique. Among 1697 proteins identified, 1193 with robust assay readouts were used for quantitative analyses. Differential expression analyses identified 154 upregulated and 227 downregulated proteins in the EV-positive group. Functional analyses showed that the upregulated proteins are mainly related to activities of lymphocytes and cytokines, inflammation, and responses to stress and viral invasion, while the downregulated proteins are mainly related to neuronal integrity and activity as well as neurogenesis. According to receiver operating characteristic analysis results, Rho-GDP-dissociation inhibitor 2 exhibited the highest sensitivity (96.2%) and specificity (100%) for discriminating EV-positive from EV-negative patients. The chemokine CXCL10 was most upregulated (>300-fold) with also high sensitivity (92.3%) and specificity (94.3%) for indicating EV positivity. Thus, this study uncovered perturbations of multiple host processes due to EV meningoencephalitis, especially the general trend of enhanced immune responses but impaired neuronal functions. The identified dysregulated proteins may also prompt biomarker development.

Cerebral HSV-1 Vasculitis as a Fatal Complication of Immunosuppression in Non-Hodgkin´s Lymphoma: A Case Report and Review of the Literature

Patients with lymphoma are predisposed to infection because of the immunocompromised state related to the disease itself and as a consequence of chemo-/radiotherapy. Here, we report a case of Herpes-simplex virus encephalitis (HSE) in an immunosuppressed patient with splenic marginal zone lymphoma (SMZL), a rare indolent variant of non-Hodgkin´s lymphoma (NHL). The course was complicated febrile neutropenia and HSV-1-related cerebral vasculitis causing progressive ischemic stroke. This case illustrates the expanding spectrum of atypical clinical and radiological manifestations of HSE in patients treated with myelotoxic drugs. Moreover, we summarize the few central nervous system manifestations of SMZL reported in the literature and discuss distinct causes of neurological deterioration in patients with NHL.

Symptom Resolution in Pediatric Patients With Lyme Disease

We performed a retrospective study to determine the time frame for symptom resolution in 78 pediatric patients hospitalized with laboratory-confirmed early-disseminated or late-stage Lyme disease. The vast majority of the patients improved promptly after receiving appropriate antibiotics. Patients with a longer duration of arthritis before the institution of therapy experienced a longer time to recovery.

Molecular characterization of viruses associated with encephalitis in São Paulo, Brazil

The objective of this study was to characterize the prevalence of viral encephalitis due to arbovirus infection of the Togaviridae and Flaviviridae families in São Paulo, Brazil. A total of 500 cerebrospinal fluid (CSF) samples collected between August 2012 and January 2013, from patients with symptoms of acute encephalitis were analyzed. Findings suggestive of viral encephalitis-elevations in cell concentration, glucose and total protein-were observed in 234 (46.8%) samples, designated as Group 1. The remaining 266 samples comprised Group 2. All samples were tested for Flaviviruses (dengue virus 1, 2, 3 and 4, yellow fever virus and West Nile virus), Alphavirus (NS5 region) and enterovirus by RT- PCR and for herpesviruses and enteroviruses using CLART-Entherpex. A presumptive viral etiological agent was detected in 26 samples (5.2%), 18 (8.0%) in Group 1 and 8 (3.0%) in Group 2. In Group 1 human herpesviruses were detected in 9 cases, enteroviruses in 7 cases, dengue viruses (DENV) in 2 CSFs and St. Louis encephalitis virus (SLEV) in one case. In Group 2 there were 3 CSFs positive for human herpesviruses, 2 for enteroviruses, 2 for DENV and 1 for SLEV. Detection of arboviruses, even though present in a minority of infected patients, identifies these viruses as a probable etiological agent of encephalitis. This is of special concern in regions where this class of viruses is endemic and has been linked to other recent epidemics.

Peripheral Blood Biomarkers of Disease Outcome in a Monkey Model of Rift Valley Fever Encephalitis

Rift Valley Fever (RVF) is an emerging arboviral disease of livestock and humans. Although the disease is caused by a mosquito-borne virus, humans are infected through contact with, or inhalation of, virus-laden particles from contaminated animal carcasses. Some individuals infected with RVF virus (RVFV) develop meningoencephalitis, resulting in morbidity and mortality. Little is known about the pathogenic mechanisms that lead to neurologic sequelae, and thus, animal models that represent human disease are needed. African green monkeys (AGM) exposed to aerosols containing RVFV develop a reproducibly lethal neurological disease that resembles human illness. To understand the disease process and identify biomarkers of lethality, two groups of 5 AGM were infected by inhalation with either a lethal or a sublethal dose of RVFV. Divergence between lethal and sublethal infections occurred as early as 2 days postinfection (dpi), at which point CD8+ T cells from lethally infected AGM expressed activated caspase-3 and simultaneously failed to increase levels of major histocompatibility complex (MHC) class II molecules, in contrast to surviving animals. At 4 dpi, lethally infected animals failed to demonstrate proliferation of total CD4+ and CD8+ T cells, in contrast to survivors. These marked changes in peripheral blood cells occur much earlier than more-established indicators of severe RVF disease, such as granulocytosis and fever. In addition, an early proinflammatory (gamma interferon [IFN-γ], interleukin 6 [IL-6], IL-8, monocyte chemoattractant protein 1 [MCP-1]) and antiviral (IFN-α) response was seen in survivors, while very late cytokine expression was found in animals with lethal infections. By characterizing immunological markers of lethal disease, this study furthers our understanding of RVF pathogenesis and will allow the testing of therapeutics and vaccines in the AGM model.IMPORTANCE Rift Valley Fever (RVF) is an important emerging viral disease for which we lack both an effective human vaccine and treatment. Encephalitis and neurological disease resulting from RVF lead to death or significant long-term disability for infected people. African green monkeys (AGM) develop lethal neurological disease when infected with RVF virus by inhalation. Here we report the similarities in disease course between infected AGM and humans. For the first time, we examine the peripheral immune response during the course of infection in AGM and show that there are very early differences in the immune response between animals that survive infection and those that succumb. We conclude that AGM are a novel and suitable monkey model for studying the neuropathogenesis of RVF and for testing vaccines and therapeutics against this emerging viral pathogen.

Aseptic meningitis in adults and children: Diagnostic and management challenges

BACKGROUND

Aseptic meningitis represents a common diagnostic and management dilemma to clinicians.

OBJECTIVES

To compare the clinical epidemiology, diagnostic evaluations, management, and outcomes between adults and children with aseptic meningitis.

STUDY DESIGN

We conducted a retrospective study from January 2005 through September 2010 at 9 Memorial Hermann Hospitals in Houston, TX. Patients age≥2months who presented with community-acquired aseptic meningitis with a CSF white blood cell count >5cells/mm³ and a negative Gram stain and cultures were enrolled. Patients with a positive cryptococcal antigen, positive blood cultures, intracranial masses, brain abscesses, or encephalitis were excluded.

RESULTS

A total of 509 patients were included; 404 were adults and 105 were children. Adults were most likely to be female, Caucasian, immunosuppressed, have meningeal symptoms (headache, nausea, stiff neck, photophobia) and have a higher CSF protein (P <0.05). In contrast, children were more likely to have respiratory symptoms, fever, and leukocytosis (P <0.05). In 410 (81%) patients, the etiologies remained unknown. Adults were more likely to be tested for and to have Herpes simplex virus and West Nile virus while children were more likely to be tested for and to have Enterovirus (P <0.001). The majority of patients were admitted (96.5%) with children receiving antibiotic therapy more frequently (P <0.001) and adults receiving more antiviral therapy (P=0.001). A total of 384 patients (75%) underwent head CT scans and 125 (25%) MRI scans; all were normal except for meningeal enhancement. All patients had a good clinical outcome at discharge.

DISCUSSION

Aseptic meningitis in adults and children represent a management challenge as etiologies remained unknown for the majority of patients due to underutilization of currently available diagnostic techniques.